1. Field of the Invention
This invention pertains generally to a bioprosthetic heart valve and, more particularly, a tri-composite, full root, stentless valve.
2. Description of the Related Art
Prosthetic heart valves are frequently used to replace failed heart valves. There are two broad categories of prosthetic heart valves: mechanical and tissue. Mechanical heart valves are quite durable, but require anti-coagulation therapy to prevent blood clotting in the patients receiving them. Tissue valves, or xe2x80x9cbioprostheticxe2x80x9d heart valves, are therefore commonly preferred over mechanical valves.
Each of the known types of bioprosthetic heart valve also has its peculiar limitations. For instance, homografts from donor human hearts are difficult to obtain in exact sizes, cannot be sterilized, and require extensive tests to determine the risks of transmitting diseases and of donor tissue incompatibility. Xenografts, or bioprostheses procured from animals other than humans, provide an acceptable alternative to homografts because they can be provided in acceptable quantities and in a variety of sizes, and they can be sterilized and tested for disease. Thus, xenografts are generally preferred over homografts. Among xenografts, porcine is generally preferred, although other types of xenografts, such as bovine, ostrich, and kangaroo, are known.
Animal valves are commonly trimmed by cutting away the aortic wall between the leaflets and leaving only the tissue to which leaflets are attached. To support the remaining structure, animal valves are usually supported by metallic or plastic xe2x80x9cstents.xe2x80x9d A stent is a structural support, or frame, for the tissue that actually forms the valve. Typically, the valve tissue is stitched to cloth covering the stent(s). The cloth covers and is attached to the stent principally to provide a basis for attaching the tissue. The stent is often augmented by a sewing ring usually attached to the exterior of the prosthesis to aid in surgical attachment into the patient""s aorta. The sewing ring and/or stent occupies space in the patient""s annulus, thereby reducing the orifice area of the valve and consequently increasing turbulence and the pressure gradient. In addition, the stent tends to be somewhat rigid, requiring the leaflets to absorb much of the stress during valve closure.
Stentless tissue valves have relatively superior hemodynamics, i.e., fluid flow characteristics of blood through the valve, and potential for improved durability. A variety of stentless valves are generally known, including those disclosed in the following patents: U.S. Pat. No. 5,336,258, entitled xe2x80x9cStentless Heart Valve and Holder,xe2x80x9d issued Aug. 9, 1994, to Baxter International, Inc. as the assignee of the inventors Quintero, et al.; U.S. Pat. No. 5,156,621, entitled xe2x80x9cStentless Bioprosthetic Cardiac Valve,xe2x80x9d issued Oct. 20, 1992, to the inventors Navia, et al.; and U.S. Pat. No. 4,666,442, entitled xe2x80x9cCardiac Valve Prosthesis with Valve Flaps of Biological Tissue,xe2x80x9d issued May 19, 1987, to Sorin Biomedia S.p.A. as the assignee of the inventors Arru et al.
However, each of these valves suffers some drawbacks. For instance, each porcine aortic valve comprises a single xenograft, i.e., the entire valve is extracted whole from the donor and implanted into the recipient. Thus, they are of uneven dimension. This is particularly problematical in that the valve leaflets will typically be of different sizes. Although this is natural in porcine valves, it does have some undesirable ramifications on operations and function.
The present invention is directed to resolving one or all of the problems mentioned above.
A bioprosthetic heart valve is disclosed. In a first aspect of the invention, a prosthetic heart valve comprises three mammalian heart valve leaflets, each valve leaflet including a full root length of tissue, the valve leaflets being affixed to one another to define a fluid flow passage, the fluid flow through which may be governed by the valve leaflets. In a second aspect the heart valve comprises a plurality of heart valve leaflets affixed to one another to define a fluid flow passage, the fluid flow through which may be governed by the valve leaflets; and a trimming guide on at least one of the plurality of valve leaflets. In yet a third aspect of the invention, a bioprosthetic heart valve comprises a plurality of assembled parts, wherein the assembled parts are sutured together by hidden and locked stitching.